Down’s syndrome screening does not pass, which means that the Down’s syndrome screening result is high or critical risk. The main reasons for not passing the Down’s syndrome screening are the following: a. The age of the pregnant woman is one of the main reasons for not passing the Down’s syndrome screening. The older the pregnant woman is, the worse the ovarian tract function is and the quality of the follicles decreases accordingly. The chance of failing the Down’s syndrome screening test is significantly higher after pregnancy. Generally speaking, it is not meaningful to do Down’s syndrome screening for pregnant women above the age of 35, and it is better to do DNA testing directly. Second, when pregnant women undergo Down’s syndrome screening, the age, weight and gestational week provided do not exactly match the actual, making the results of Down’s syndrome screening inaccurate. Third, when the Down’s syndrome screening is done, the pregnant woman’s health condition is not very good, such as the pregnant woman is catching a cold, which will affect the accuracy of the test results.